Hi Paul,
What you want is "Designer". The "Form Editor" is CRM Customization which changes the layout of the Web Content Entity you're looking at. If you can go into the "Designer", next click on the "Actions" tab and you can drag and drop over the "Auto Responder" and fill it out there. This article has more information: http://help.clickdimensions.com/form-actions-for-clickdimensions-forms-and-surveys/
Thanks for using the forum and please let us know if you have questions!